# canvas.realtime.activity.begin
mutation write
Use when the requested change exactly matches canvas.realtime.activity.begin; read the current state first when a version or identifier may have changed.
## Before calling
- Authenticate as the accountable Enhance person.
- Use only resource identifiers returned by an earlier capability result or supplied by the person.
- Reuse clientToken only when retrying this exact mutation input.
## Input
Show complete JSON Schema
```json
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"canvasId": {
"type": "string",
"format": "uuid",
"pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
},
"phase": {
"type": "string",
"enum": [
"reading",
"writing",
"creating",
"deleting",
"rendering"
]
},
"nodeIds": {
"default": [],
"maxItems": 100,
"type": "array",
"items": {
"type": "string",
"minLength": 1,
"maxLength": 200
}
},
"bounds": {
"default": null,
"anyOf": [
{
"type": "object",
"properties": {
"x": {
"type": "number"
},
"y": {
"type": "number"
},
"width": {
"type": "number",
"exclusiveMinimum": 0
},
"height": {
"type": "number",
"exclusiveMinimum": 0
}
},
"required": [
"x",
"y",
"width",
"height"
],
"additionalProperties": false
},
{
"type": "null"
}
]
}
},
"required": [
"canvasId",
"phase",
"nodeIds",
"bounds"
],
"additionalProperties": false
}
```
### Example
Show example input
```json
{
"canvasId": "00000000-0000-4000-8000-000000000010",
"phase": "reading",
"nodeIds": [],
"bounds": null
}
```
## Result
Returns a typed canvas.realtime.activity.begin result from the Enhance API without transport-specific prose.
## Recovery
- BAD_REQUEST: correct the named fields and call again.
- UNAUTHORIZED: restore Enhance authentication, then retry once.
- FORBIDDEN or NOT_FOUND: list accessible resources and choose an allowed identifier.
- CONFLICT: read the current resource, merge the intended change, and retry with its version.
- INTERNAL: run Enhance diagnostics, report the failure, and stop repeating the call.
## Continue with
- Read the affected canvas resource to confirm the result.
Compatibility: `4a31f78257c63753ee160d9d17cc90e89df36dd3eb2a82259884f772360700a3`.